139,858 research outputs found
Microfluidic solvent extraction of copper from malachite-chalcopyrite mineral leach solution
No full textMicrofluidics is concerned with the characteristics and manipulation of fluid flows along mili- and micro-sized channels at very low Reynolds numbers intended for specific applications. It affords improvements based on several factors such as enhanced surface area-to-volume ratio and faster diffusion which facilitate efficient extractions and phase separations. In this study, microfluidic solvent extraction (μSX) was investigated as an alternative to conventional bulk solvent extraction of copper from a mineral leach solution. While bulk extraction typically requires a two-step mixer-settler stage, μSX precludes the need of a settler. A copper solution was produced by using sulfuric acid as leachant of a composite malachite–chalcopyrite ore. A microfluidic Y-Y channel placed on the format of a microscopy polymethylmethacrylate (PMMA) slide was used for the μSX process. LIX84 (10% v/v) dissolved in Shellsol was used as the extractant. In a typical μSX application, two streams (one is the copper leach solution and the other is the extractant) are in direct parallel contact along the microsized channel. There was no observable blockage along the microfluidic channel and copper extraction was accomplished under continuous phase flow
Spatially-localized time dependent solutions including turbulence and their interactions in 2D Kolmogorov flow
No full textIn 2D Kolmogorov flow in small aspect ratio domains, spatially-localized solutions such as kink, traveling or time-dependent kink-antikink pars coexist. However, the conservation of the flow rate in the y direction strongly restrict combination of localized solutions and their positioning. We find that by adding a homogeneous flow U y their positioning is controlled and each of localized solutions including a spatially-localized chaos is isolated. Numerical results suggest that these isolated solutions can be elements constructing a whole flow
Characteristics of overlap region in high-Reynolds number turbulent channel flow
No full textDirect numerical simulation of the fully developed turbulent channel flows have been carried out at the Reynolds number based on the friction velocity and the channel half width, 2000, 4000 and 8000. A hybrid 10th order accurate finite difference scheme in the stream and spanwise directions, and a second-order scheme in the wall-normal direction is adapted as the spatial discretization method. We observed the plateau profiles in the indicator function corresponded to the von Karman constant. Furthermore, second peak of streamwise pre-multiplied spectra were appeared in the same wall normal height, 300 < y+ < 600, in case of Re = 4000. Nevertheless, the effects of the lager than the channel half height scale on the streamwise turbulent intensity are fixed contributions without dependence on Reynolds number. These results suggested that the new streamwise vortexes are formed between buffer layer and outer layer with increasing of Reynolds number
La 'circunstancia' de 'Herederos y Pretendientes
No full textIn June 2010, the Ortega y Gasset Foundation hosted a Conference about the “Spanish Philosophical Transition” in order to debate the book of Francisco Vázquez, La filosofía española. Herederos y Pretendientes. Una lectura sociológica (1963-1990), recently published. This paper is the author’s response to criticism raised in the Conference and to published reviews received by this book. First, the author summarized the argument of Herederos y pretendientes. Secondly he responds and takes into account the most important objections against the book’s hypothesis and methodology. Finally the author evaluates the favorable judgments received by the book and suggests the limits of the historian’s task.Fundación Ortega y Gasset-Marañó
Evaluación de eficiencia y transferencia de masa en un extractor pulsado con relleno
No full textO presente trabalho tem por objetivo investigar os parâmetros operacionais no desempenho de uma coluna de extração pulsada com recheio de anéis de Raschig. Para alcançar o objetivo proposto, foi utilizado o sistema água + ácido acético + 1-butanol a 25°C e 1 atm. Após os experimentos o desempenho da coluna foi avaliado a partir do cálculo da eficiência e do coeficiente global de transferência de massa. Os modelos de Murphree (1925) e Kawase (1990) foram utilizados para o cálculo da eficiência. Os modelos escolhidos apresentaram valores coerentes. Já para o cálculo do coeficiente global de transferência de massa utilizou-se seis modelos distintos: Plug Flow Model (PFM), Safari et al. (2012), Kister (1992), Torab-Mostaedi e Safdari (2009b), Modelo de difusão e GhaffariTooran et al. (2009). Sendo que os modelos de Torab-Mostaedi e Safdari (2009b) e GhaffariTooran et al. (2009) não apresentaram valores coerentes. Com a análise dos resultados, notou-se que tanto para eficiência quanto para o coeficiente global de transferência de massa houve uma influência positiva dos parâmetros operacionais analisados. Sendo a razão das vazões quem mais influenciou na eficiência da coluna, apresentando um aumento percentual de 33,57%. Por fim, um modelo empírico foi desenvolvido com o intuito de correlacionar a eficiência da coluna com os parâmetros operacionais. A equação mostrou boa concordância com a equação de Murphree, apresentando um desvio médio de 7,35%. Assim foi possível constatar a eficácia da inserção do recheio e da pulsação na extratora como uma forma de potencializar a transferência de massa.Liquid-liquid extraction, or solvent extraction, is a unitary operation designed to separate one or more components from the insertion of a liquid phase that has more affinity with the components of interest. It is a technique used in various industrial process including the food industry, petrochemical and biochemical. Thus, the present work aims to investigate the operational parameters in the performance of a pulsed packed extraction column. The packed used in the extractor ir Raschig’s rings. For this, 30 runs were performed with aqueous acetic acid solution (solute) and 1-butanol solution (solvent) in order to obtain concentration data in the extract and raffinate and with these data to calculate column efficiency and mass transfer coefficient. The Murphree (1925) and Kawase (1990) models were used to calculate the efficiency. The two models chosen for the efficiency calculation presented consistent values. For the calculation of the mass transfer coefficient, six different models were used: Plug Flow Model (PFM), Safari et al. (2012), Kister (1992), Torab-Mostaedi and Safdari (2009b), Diffusion Model and GhaffariTooran et al. (2009). Among these models, two did not present coherent values: Torab-Mostaedi and Safdari (2009b) and GhaffariTooran et al. (2009). With the analysis of the results it was noted that for both efficiency and mass transfer coefficient there was a positive influence. The flow ratio was the one that most influenced column efficiency, with a percentage increase of 33.57%. Finally, an empirical model was developed to correlate column efficiency with operational parameters. The equation showed good agreement with the Murphree equation, presenting an average deviation of 7.35% which is a relatively low deviation. Thus it was possible to verify the usefulness of the packed insertions and pulsation in the extractor as a way to improve the mass transfer.El presente trabajo tiene como objetivo investigar los parámetros operativos en el rendimiento de una columna de extracción pulsada de relleno, el relleno utilizado fue anillos de Raschig. Para lograr los objetivos propuestos, se usó el sistema de agua + ácido acético + 1-butanol a 25°C y 1 atm. Después de los experimentos, se evaluó el rendimiento de la columna a partir del cálculo de eficiencia y el coeficiente de transferencia de masa. Se utilizaron los modelos Murphree (1925) y Kawase (1990) para calcular la eficiencia. Los modelos elegidos presentaron valores coherentes. Para el cálculo del coeficiente de transferencia de masa, se utilizaron seis modelos diferentes: Plug Flow Model (PFM), Safari et al. (2012), Kister (1992), Torab-Mostaedi e Safdari (2009b), Modelo de difusión y Ghaffari Toooran et al. (2009). Torab-Mostaedi y Safdari (2009b) y GhaffariTooran et al. (2009) no presentaron valores coherentes. Con el análisis de los resultados, se observó que tanto para la eficiencia como para el coeficiente de transferencia de masa había una influencia positiva de los parámetros operativos analizados. La relación de flujo fue la que más influyó en la eficiencia de la columna, con un aumento porcentual del 33,57%. Finalmente, se desarrolló un modelo empírico para correlacionar la eficiencia de la columna con los parámetros operativos. La ecuación mostró un buen acuerdo con la ecuación de Murphree, presentando una desviación promedio de 7,35%. Por lo tanto, fue posible verificar la eficiencia de la inserción de relleno y la pulsación en la columna de extracción como una forma de mejorar la transferencia de masa
Comparison Between Hesperidin, Coumarin, and Deferoxamine Iron Chelation and Antioxidant Activity Against Excessive Iron in the Iron Overloaded Mice
No full textObjective: Iron accumulation in the brain leads to the development of Alzheimer�s and Parkinson�s diseases. Nowadays, iron chelation therapy is the best way to decrease the side effects of iron and amyloid plaques accumulation. Iron chelators are commonly used for the treatment of Alzheimer�s disease. Previous studies have shown that natural products such as phenol and flavonoid compounds could chelate heavy metals. In the current study, we examined the iron chelation activity of hesperidin and coumarin on the brain tissue of iron-overloaded mice. Methods: 48 NMRI male mice were divided into eight groups (n = 6). Six groups were treated with iron dextran (100 mg/kg/day) four times a week for 6 weeks. After stopping the injections for a month, five groups of iron-overloaded mice were treated with hesperidin, coumarin, and desferal four times a week subsequent for four subsequent weeks. Finally, the mice were anesthetized, and blood samples were collected from the ventricle of the heart for subsequent examination. The brain tissues were isolated and fixed in the 4 paraformaldehyde solution for Perl�s staining. Results: The results show that hesperidin and coumarin could strongly chelate excessive iron from the serum and deposit iron from the brain tissue compared to desferal group. Catalase and super oxidase activity were decreased in the iron-overloaded group, but in the treated group by hesperidin and coumarin, the enzyme�s activity was increased significantly. Conclusion: Hesperidin and coumarin, as natural products, are powerful options to chelate iron ions and increase the activity of antioxidant enzymes. Copyright © 2022 Aalikhani, Safdari, Jahanshahi, Alikhani and Khalili
FITC-conjugated single chain Nimotuzumab can specifically recognize and enter EGFR-overexpressing cells
No full textThe epidermal growth factor receptor (EGFR) is regarded as an ideal target for cancer therapy and imaging. EGFR-targeting antibodies or antibody fragments can be engaged to specifically deliver small molecules with therapeutic or diagnostic properties to EGFR-overexpressing cancer cells. Cell-penetrating peptides (CPPs) are short amino acid sequences that are added to drug carriers or recombinant proteins and are believed to increase cellular internalization. In the current study, we evaluated the ability of FITC-conjugated single-chain Nimotuzumab molecules (containing or lacking CPP) in recognizing and entering EGFR-overexpressing cancer cells. The molecules were found to enter the cancer cells in an efficient manner and emit signals. No obvious difference was found between CPP-containing and CPP-lacking molecules in entering cancer cells. © 2022, The Author(s), under exclusive licence to Springer Nature B.V
Author self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
Overview of the Author Profiling Task at PAN 2013
No full text[EN] This overview presents the framework and results for the Author Profiling
task at PAN 2013. We describe in detail the corpus and its characteristics,
and the evaluation framework we used to measure the participants performance to
solve the problem of identifying age and gender from anonymous texts. Finally,
the approaches of the 21 participants and their results are described.The author profiling task @PAN-2013 was an activity of the WIQ-EI IRSES project (Grant No. 269180) within the FP 7 Marie Curie People Framework of the European Commission. We want to thank the Forensic Lab of the Universitat Pompeu Fabra Barcelona for sponsoring the award for the winner team. The work of the first author was partially funded by Autoritas Consulting SA and by Ministerio de Economía y Competitividad de España under grant ECOPORTUNITY IPT-2012-1220-430000. The work of the second author was in the framework the DIANA-APPLICATIONS-Finding Hidden Knowledge in Texts: Applications (TIN2012-38603-C02-01) project, and the VLC/CAMPUS Microcluster on Multimodal Interaction in Intelligent Systems. The work of fifth author was funded in part by the Swiss National Science Foundation (SNF) project "Mining Conversational Content for Topic Modelling and Author Identification (ChatMiner)" under grant number 200021_130208.Rangel, F.; Rosso, P.; Koppel, M.; Stamatatos, E.; Inches, G. (2013). Overview of the Author Profiling Task at PAN 2013. CLEF Conference on Multilingual and Multimodal Information Access Evaluation. 352-365. https://riunet.upv.es/handle/10251/46636S35236
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
- …
